1. Field of the Invention
The present general inventive concept relates to a method of fabricating an ink jet head and an ink jet head fabricated thereby and, more particularly, to a method of fabricating an ink jet head and an ink jet head fabricated thereby, provided with an inserting layer pattern to flatten a nozzle layer.
2. Description of the Related Art
An ink jet recording device functions to print an image by ejecting fine droplets of ink for printing to a desired position on a recording medium. Such an ink jet recording device has been widely used since its price is low and numerous kinds of colors may be printed at a high resolution. The ink jet recording device basically includes an ink jet head for actually ejecting the ink and an ink container in fluid communication with the ink jet head. The ink stored in the ink container is supplied into the ink jet head through an ink supply hole, and the ink jet head ejects the ink supplied from the ink container onto the recording medium to thereby complete the printing operation.
A process of fabricating the ink jet head may be classified into a hybrid type and a monolithic type depending upon a method of forming a chamber layer and a nozzle layer configuring the ink jet head. In the case of the hybrid type, a process of forming the chamber layer on a substrate having a pressure-generating element, such as a heat-generating unit, and a process of forming the nozzle layer having a nozzle for ejecting the ink are individually progressed. Next, the nozzle layer is adhered on the chamber layer to thereby complete the fabrication of the ink jet head. However, in the process of adhering the nozzle layer on the chamber layer, misalignment between the pressure-generating element and the nozzle is likely to occur. In addition, the process becomes complicated since the chamber layer and the nozzle layer are fabricated through different processes. To overcome these problems, a method fabricating the monolithic type ink jet head has been widely employed.
FIGS. 1 to 4 are cross-sectional views illustrating a method of fabricating a conventional monolithic type ink jet head.
Referring to FIG. 1, a heat-generating unit 102 for ink ejection is formed on a substrate 100. Next, a positive photoresist layer is formed on an entire surface of the substrate, and then the positive photoresist layer is exposed and developed to form a mold layer 104 on the substrate 100, for covering a region where a flow path is to be formed.
Referring to FIG. 2, a negative photoresist layer 106 is formed on the entire surface of the substrate 100 having the mold layer 104. As shown in FIG. 2, during the fabrication process, the negative photoresist layer 106 has an uneven thickness due to a step-difference formed between the substrate 100 and the mold layer 104. In particular, the thickness of the negative photoresist layer 106 becomes rapidly thinned at an upper portion of an edge portion E of the mold layer 104.
Referring to FIG. 3, the negative photoresist layer 106 is exposed by a photomask provided with a nozzle pattern, and patterned by a development process. As a result, as shown in FIG. 3, a flow path structure 106′ has at least one nozzle 108 for ejecting the ink formed at the upper portion thereof.
Referring to FIG. 4, the substrate 100 is etched to form an ink supply hole 110 passing through the substrate 100, and then the mold layer 104 is removed using an appropriate solvent. As a result, an ink chamber 112 and a restrictor 114 are formed at a region where the mold layer 104 was removed.
As described above, according to the conventional method, the mold layer 104 is previously formed at the region where the flow path including the ink chamber 112 and the restrictor 114 is to be formed, and then the negative photoresist layer 106 is formed. As a result, as shown in FIG. 4, the flow path structure 106′ fabricated by the process described above has an uneven height from the substrate 100. In particular, the flow path structure 106′ has an uneven thickness at an upper portion of the flow path including the ink chamber 112 and the restrictor 114. That is, the thickness of the flow path structure 106′ becomes thinner as it gets nearer to an edge of the flow path. As a result, when the nozzle 108 passing through the upper portion of the flow path structure 106′ is formed, the height of the nozzle may have an uneven distribution to deteriorate ink ejection properties. In addition, as the thickness of the flow path structure 106′ becomes rapidly thin at the edge portion E of the flow path, when pressure generated at the time the ink is ejected is repeatedly applied, the flow path structure 106′ on the edge portion E of the flow path may have mechanical defects.